The National Oceanic and Atmospheric Administration has been reopening segments of offshore Gulf waters in stages since July, starting with areas farthest away from the Deepwater Horizon oil spill site. The agency has done seven different openings since July 22. Today's is the fourth in a month.

The newly-opened area stretches from the Mississippi River delta west to around Morgan City. The opening came after a safety and seafood testing protocol agreed to by NOAA, the federal Food and Drug Administration and each Gulf state.

NOAA first started sampling the area July 27 but stopped after scientists saw oil on the water's surface. Once the area was deemed largely free of visible oil, scientists began sampling again for a month starting Aug. 15.

NOAA and the FDA conducted chemical tests of more than 250 shrimp and fish samples, and smell tests on more than 100 samples. All testing showed that there were no oil or dispersant levels anywhere near levels of concern, according to NOAA.

Still, 11 percent of federal waters in the Gulf remain closed to fishing, including areas closest to the well site and areas southeast of the well. Nearly 37 percent of the Gulf was closed to fishing at the peak of the spill event, in June.